Cytotoxic and antivascular 1-methyl-4-(3-fluoro-4-methoxyphenyl)-5-(halophenyl)-imidazoles

An overview of imidazole and its analogues as potent anticancer agents

The quest for novel, physiologically active imidazoles remains an exciting topic of research among medicinal chemists. The imidazole ring is a five-membered aromatic heterocycle that is found in both natural and synthesized compounds. Multiple anticancer drug classes are currently available on the market, but concerns including toxicity, limited efficacy and solubility have lowered the overall therapeutic index. Therefore, the hunt for new potential chemotherapeutic agents persists. The development of imidazole as a reliable and safer alternative to anticancer treatment is generating much attention among experts. Tubulin or microtubule polymerization inhibition and changes in the structure and function of DNA, VEGF, topoisomerase, kinases, histone deacetylases and certain other proteins that affect gene expression are among the putative targets.

Synthesis and biological evaluation of novel 5-substituted/unsubstituted triazolothiadiazines as tubulin depolymerizing and vascular disrupting agents with promising antitumor activity

A novel series of 5-substituted/unsubstituted [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine compounds has been achieved successfully through chemoselective reduction of the C = N bond, based on our prior work. Initial biological evaluation illustrated that the most active derivative 7j exhibited significant cell growth inhibitory activity toward MCF-7, A549, HCT116, and A2780 with the IC50 values of 0.75, 0.94, 2.90, and 4.15 μM, respectively. Most importantly, all the representative analogs did not demonstrate obvious cytotoxic activity against the non-tumoural cell line HEK-293 (IC50  > 100 μM). The mechanism study revealed that 7j caused the G2 /M phase arrest, induced cell apoptosis in HeLa cells in a concentration-dependent manner, and also showed potent tubulin polymerization inhibitory effect. Meanwhile, 7j exerted significant antivascular activity in the wound-healing and tube formation assays. These observations indicate that 5-unsubstituted 6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine scaffold might be considered as a potential lead for antitubulin inhibitors to develop highly efficient anticancer agents with potent selectivity over normal human cells.

Triarylpyrazole Derivatives as Potent Cytotoxic Agents; Synthesis and Bioactivity Evaluation "Pyrazole Derivatives as Anticancer Agent"

BACKGROUND

During the last recent years, several anti-cancer agents were introduced for the treatment of diverse kinds of cancer. Despite their potential in the treatment of cancer, drug resistance and adverse toxicity such as peripheral neuropathy are some of the negative criteria of anti-cancer agents and for this reason, the design and synthesis of new anti-cancer agents are important.

OBJECTIVE

Design, synthesis, and anticancer activity evaluation of some pyrazole derivatives.

METHODS

A series of Target compounds were prepared using multistep synthesis. Their cytotoxic activity against three different human cancer cell lines namely human colon carcinoma cells (HT-29), epithelial carcinoma cells (U-87MG), pancreatic cancerous cells (Panc-1) as well as AGO1522 normal cell line using in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was investigated.

RESULTS

1,3-Diaryl-5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazole and 1,3-Diaryl-5-(3,4,5-trimethoxyphenyl)- 1H-pyrazole were synthesized in good yields and their structure and purity were confirmed using ¹H-NMR, ¹³C-NMR, and elemental analysis. Generally, the synthesized scaffolds exhibited good cytotoxicity against cancerous cell lines in comparison to the reference standard, paclitaxel. Compounds 3A: and 3C: , in Annexin V/ PI staining assay, exerted remarkable activity in apoptosis induction in HT-29 cell lines. Both of them also led to cell cycle arrest in the sub-G1 phase which is inconsistent with the results of apoptosis assay.

CONCLUSION

Concerning obtained results, it is interesting to synthesis more pyrazole derivatives as anticancer agents.

Synthesis, biological evaluation, and modeling studies of 1,3-disubstituted cyclobutane-containing analogs of combretastatin A4

With the aim of circumventing the adverse cis/trans-isomerization of combretastatin A4 (CA4), a naturally occurring tumor-vascular disrupting agent, we designed novel CA4 analogs bearing 1,3-cyclobutane moiety instead of the cis-stilbene unit of the parent compound. The corresponding cis and trans cyclobutane-containing derivatives were prepared as pure diastereomers. The structure of the target compounds was confirmed by X-ray diffraction study. The title compounds were evaluated for their cytotoxic properties in human cancer cell lines HepG2 (hepatocarcinoma) and SK-N-DZ (neuroblastoma), and the overall activity was found in micromolar range. Molecular docking studies and molecular dynamics simulation within the colchicine binding site of tubulin were in good agreement with the obtained cytotoxicity data.

New naphthopyran analogues of LY290181 as potential tumor vascular-disrupting agents

A series of 19 analogues of the antiproliferative naphthopyran LY290181 were prepared for structure-activity relationship studies. We found the best activities for test compounds bearing small substituents at the meta position of the phenyl ring. The mode of action of LY290181 and eight new analogues was studied in detail. The compounds were highly anti-proliferative with IC₅₀ values in the sub-nanomolar to triple-digit nanomolar range. The new analogues led to G2/M arrest due to interruption of the microtubule dynamics. In 518A2 melanoma cells they caused a mitotic catastrophe which eventually led to apoptosis. The naphthopyrans also induced a disruption of the vasculature in the chorioallantoic membrane (CAM) of fertilized chicken eggs as well as in xenograft tumors in mice. In a preliminary therapy trial, the difluoro derivative 2b retarded the growth of resistant xenograft tumors in mice.

Crystal structure of 1-(2H-1,3-benzodioxol-5-yl)-3-(1H-imidazol-1-yl)propan-1-one, C13H12N2O3

C13H12N2O3, monoclinic, P21/n (no. 14), a = 7.3322(5) Å, b = 8.0341(5) Å, c = 19.4479(14) Å, β = 95.775(2)°, V = 1139.82(13) Å3, Z = 4, R gt(F) = 0.0533, wR ref(F 2) = 0.1335, T = 293(2) K.

Silver-Catalyzed Isocyanide-Isocyanide [3+2] Cross-Cycloaddition Involving 1,2-Group Migration: Efficient Synthesis of Trisubstituted lmidazoles

Imidazole ring is an important five-membered aromatic heterocycle that is widely present in natural products and synthetic molecules. The isocyanide-isocyanide [3+2] cross-cycloaddition reaction constitutes a straightforward method to access imidazoles starting from the easily available chemicals. So far, only three successive reports are known and all lead to the formation of 1,4-disubstituted imidazoles. Here, we report the first isocyanide-isocyanide [3+2] cross-cycloaddition reaction allowing for the formation of 1,4,5-trisubstituted imidazoles under silver catalysis. An unexpected 1,2-migration of sulfonyl, alkoxycaybonyl, and carbamoyl groups took place during the cyclization process that is responsible for the formation of trisubstituted imidazoles. This report displayed a mechanistically novel synthetic method toward a variety of imidazole derivatives, which are otherwise difficult to access by conventional methods.

Combretastatin A-4 derived 5-(1-methyl-4-phenyl-imidazol-5-yl)indoles with superior cytotoxic and anti-vascular effects on chemoresistant cancer cells and tumors

5-(1-Methyl-4-phenyl-imidazol-5-yl)indoles 5 were prepared and tested as analogs of the natural vascular-disrupting agent combretastatin A-4 (CA-4). The 3-bromo-4,5-dimethoxyphenyl derivative 5c was far more active than CA-4 with low nanomolar IC50 concentrations against multidrug-resistant KB-V1/Vbl cervix and MCF-7/Topo mamma carcinoma cells, and also against CA-4-resistant HT-29 colon carcinoma cells. While not interfering markedly with the polymerization of tubulin in vitro, indole 5c completely disrupted the microtubule cytoskeleton of cancer cells at low concentrations. It also destroyed real blood vessels, both in the chorioallantoic membrane (CAM) of fertilized chicken eggs and within tumor xenografts in mice, without harming embryo or mouse, respectively. Indole 5c was less toxic than CA-4 to endothelial cells, fibroblasts, and cardiomyocytes. In highly vascularized xenograft tumors 5c induced distinct discolorations and histological features typical of vascular-disrupting agents, such as disrupted vessel structures, hemorrhages, and extensive necrosis. In a first preliminary therapy trial, indole 5c retarded the growth of resistant xenograft tumors in mice. © 2016 Elsevier Science Ltd. All rights reserved.

Combretastatin A-4 derived imidazoles show cytotoxic, antivascular, and antimetastatic effects based on cytoskeletal reorganisation

INTRODUCTION

Combretastatin A-4 (CA-4) is a natural cis-stilbene which interferes with the cellular tubulin dynamics and which selectively destroys tumour blood vessels. Its pharmacological shortcomings such as insufficient chemical stability, water solubility, and cytotoxicity can be remedied by employing its imidazole derivatives.

METHODS

We studied 11 halogenated imidazole derivatives of CA-4 for their effects on the microtubule and actin cytoskeletons of cancer and endothelial cells and on the propensity of these cells to migrate across tissue barriers or to form blood vessel-like tubular structures.

RESULTS

A series of N-methyl-4-aryl-5-(4-ethoxyphenyl)-imidazoles proved far more efficacious than the lead CA-4 in growth inhibition assays against CA-4-resistant HT-29 colon carcinoma cells and generally more selective for cancer over nonmalignant cells. Et-brimamin (6), the most active compound, inhibited the growth of various cancer cell lines with IC50 (72 h) values in the low nanomolar range. Active imidazoles such as 6 reduced the motility and invasiveness of cancer cells by initiating the formation of actin stress fibres and focal adhesions as a response to the extensive microtubule disruption. The antimetastatic properties were ascertained in 3D-transwell migration assays which simulated the transgression of highly invasive melanoma cells through the extracellular matrix of solid tumours and through the endothelium of blood vessels. The studied imidazoles exhibited vascular-disrupting effects also against tumour xenografts that are refractory to CA-4. They were also less toxic and better tolerated by mice.

CONCLUSIONS

We deem the new imidazoles promising drug candidates for combination regimens with antiangiogenic VEGFR inhibitors.

4,5-Diaryl imidazoles with hydroxamic acid appendages as anti-hepatoma agents

INTRODUCTION

Hepatocellular carcinoma (HCC) is the most abundant tumour of the liver with rising patient numbers in the Western world countries. Despite newly approved drugs like protein kinase inhibitors the survival rate is still poor.

METHODS

In order to identify potential new drugs for the treatment of HCC we investigated the real-time cell viability, apoptosis induction (sub-G1 cells), and HDAC (histone deacetylase) activity of two hepatocellular cancer cell lines HepG2 and Hep3B treated with new imidazole-tethered hydroxamates.

RESULTS

The tested cinnamyl hydroxamates exhibited significant antiproliferative and cytotoxic activity in HCC cells as apparent from high sub-G1 cell levels in flow cytometric cell cycle analyses. In Hep3B cells HDAC inhibition was observed comparable in magnitude to that induced by the clinically applied HDAC inhibitor SAHA (Zolinza, Vorinostat).

CONCLUSIONS

The new imidazolyl hydroxamic acids lend themselves as a possible alternative to SAHA in the therapy of HCC. Even more so since similar 4,5-diarylimidazoles lacking only the hydroxamate functionality were previously shown in animal studies to be well tolerated and orally applicable.

Comprehensive review in current developments of imidazole-based medicinal chemistry

Imidazole ring is an important five-membered aromatic heterocycle widely present in natural products and synthetic molecules. The unique structural feature of imidazole ring with desirable electron-rich characteristic is beneficial for imidazole derivatives to readily bind with a variety of enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. The related research and developments of imidazole-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous imidazole-based compounds as clinical drugs have been extensively used in the clinic to treat various types of diseases with high therapeutic potency, which have shown the enormous development value. This work systematically gives a comprehensive review in current developments of imidazole-based compounds in the whole range of medicinal chemistry as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents, together with their potential applications in diagnostics and pathology. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic imidazole-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.

Synthesis of 1,5-diarylhaloimidazole analogs and their inhibitory activities against PGE₂ production from LPS-treated RAW 264.7 cells

A number of 1,5-diarylimidazole analogs were synthesized and evaluated their inhibitory activities of cyclooxygenase-2 catalyzed prostaglandin E(2) production. Reactions of 1,5-diarylimidazoles with halogenating reagents (NCS, NBS, NIS) afforded halogenated analogs. Among the analogs tested, compounds Ib, IIa, IIb and IIe exhibited significantly improved inhibitory activities against COX-2-mediated PGE(2) production from LPS-induced RAW 264.7 cells compared to those of the parent 1,5-diarylimidazoles. Especially, the analogs Ib (IC(50)=0.55 μM) and IIa (IC(50)=0.58 μM) showed best results. Halogenation on the 1,5-diarylimidazole ring enhanced inhibitory activities against COX-2 catalyzed PGE(2) production, however, inhibitory activities were significantly varied by position(s) and species of the substituted halogen(s).